AP Bio Unit 7 Evolution

What is a common ancestor?

A species of organism from which one or more new species evolves.

What fundamental features do all living organisms share?

All use DNA for storing genetic material and all use glycolysis.

What are the characteristics that all living eukaryotes share?

They all have membrane-bound organelles, contain linear chromosomes, and have genes that contain introns.

How does the recency of a common ancestor affect species relatedness?

A more recent common ancestor indicates species are more closely related.

What are cladograms?

Diagrams that illustrate common ancestry, also known as phylogenetic trees.

What types of data provide evidence for evolution?

Biogeography, anatomical homologies, developmental homologies, molecular homologies, and the fossil record.

What is biogeography?

The study of where organisms live now and where their common ancestors lived in the past.

How does biogeography support common ancestry?

It illustrates patterns of common evolution among ancestors and their descendant species.

What is the significance of anatomical homologies?

They are evidence that species evolved from a common ancestor.

What are homologous structures?

Structures that are similar in shape among related species but do not serve the same purpose.

What is the difference between homologous and analogous structures?

Homologous structures suggest common ancestry, while analogous structures evolved independently to perform the same function.

What are vestigial structures?

Body parts that have no apparent function and appear to be residual parts from a past ancestor.

What do developmental homologies indicate?

Similarities in the development of offspring among species that share common ancestry.

What do molecular similarities reveal about species?

Species with similar DNA and amino acid sequences share a common ancestor.

What does a greater difference in DNA sequences indicate?

Less relatedness to other species.

What are fossils?

Preserved remains of ancient species that provide evidence for evolution.

What is the best evidence for evolution?

Molecular similarities, such as DNA and amino acid sequences.

How do anatomical homologies support evolution?

They show that species are related and help explain how they evolved.

What is the role of the fossil record in evolution?

It provides evidence of ancient species and their changes over time.

What does the study of biogeography reveal about marsupials in Australia?

They evolved from a common ancestor on that continent and were isolated from other mammal lineages.

How do camel species illustrate common ancestry?

Different camel species suggest they all originated from a common ancestor in North America and migrated to diverse regions.

What is radiometric dating?

A method used to determine the age of fossils by measuring the decay of radioactive isotopes.

What percentage of all animals that ever existed are estimated to have been preserved as fossils?

Less than 1%.

What is preservation bias in the context of fossils?

Only hard parts like bones and shells are usually preserved as fossils.

What does the fossil record provide evidence for?

The order in which ancient species evolved.

What are the three patterns of evolution identified in the fossil record?

Adaptive Radiation, Gradualism, and Punctuated Equilibrium.

What is Gradualism in evolutionary theory?

A slow, steady rate of evolution in a single line of descent of species.

What is Punctuated Equilibrium?

Periods of stasis interrupted by periods of rapid evolutionary change.

What is Adaptive Radiation?

A single species evolves into many different species in different habitats during a short time period.

What is coevolution?

When two or more species reciprocally affect each other's evolution through close ecological interactions.

What is convergent evolution?

Unrelated species independently developing similar traits due to shared environmental pressures.

What is divergent evolution?

Related species evolving distinct traits from a common ancestor due to adaptation to new environments.

What is a mass extinction event?

When a large number of species (over 75%) go extinct in a short time.

What are some causes of mass extinction?

Climate change, asteroids, volcanic eruptions, and human impact.

How does ecological stress affect extinction rates?

High ecological stress leads to high rates of extinction, while low stress results in low rates.

What human activities contribute to ecological stress?

Hunting, pollution, habitat destruction, and climate change.

What is the significance of genetic diversity in species survival?

Higher genetic diversity makes species less likely to go extinct as they can better survive environmental changes.

What is adaptive radiation in the context of extinction?

When a species goes extinct, it opens ecological niches that can be filled by other species that evolve to exploit available resources.

What evidence supports ongoing evolution in populations?

Changes in DNA sequences, changes in the fossil record, and emergence of genetic resistances.

What is the sixth mass extinction?

The current extinction crisis caused by human activities, leading to species extinction rates thousands of times higher than natural rates.

What is Hardy-Weinberg Equilibrium?

A theory stating that in the absence of evolutionary forces, allele frequencies in a population will not change over time.

What conditions must be met for a population to be in Hardy-Weinberg Equilibrium?

No Natural Selection, No Gene Flow, No Mutations, No Sexual Selection, No Genetic Drift.

What does it mean if a population is evolving?

The allele frequencies within that population are changing over time.

How do scientists determine if a population is evolving?

By tracking allele frequencies across multiple generations.

What is the Hardy-Weinberg equation for allele frequencies?

p + q = 1, where p is the frequency of the dominant allele and q is the frequency of the recessive allele.

What does the Hardy-Weinberg equation for genotype frequencies state?

p² + 2pq + q² = 1, which represents the frequencies of homozygous dominant, heterozygous, and homozygous recessive genotypes.

What does p represent in the Hardy-Weinberg equations?

The frequency of the dominant allele.

What does q represent in the Hardy-Weinberg equations?

The frequency of the recessive allele.

What happens if any conditions of Hardy-Weinberg are not met?

The population is not in Hardy-Weinberg Equilibrium and is experiencing evolution.

Why is the Hardy-Weinberg model useful?

It provides equations to quantify allele frequency at different time points and determine if evolution is occurring.

What is the significance of observing changes in allele frequencies?

It is a measure of evolution at the population level.

What is the frequency of the recessive allele if the frequency of the dominant allele is 0.7?

The frequency of the recessive allele is 0.3.

If the frequency of the recessive allele (a) is 0.4, what is the frequency of the dominant allele (A)?

The frequency of the dominant allele is 0.6.

What does the term 'random mating' refer to in the context of Hardy-Weinberg?

It is a condition where individuals pair by chance, not by any selective criteria.

What is the relationship between genotype frequencies and allele frequencies in Hardy-Weinberg?

The sum of the genotype frequencies (p² + 2pq + q²) must equal the total allele frequencies (p + q = 1).

What is the Punnett square used for in the context of Hardy-Weinberg?

To show the genotypes of expected offspring based on allele frequencies.

What does the term 'genetic drift' mean?

Random changes in allele frequencies in a population, often having a more significant effect in small populations.

What is the impact of natural selection on Hardy-Weinberg Equilibrium?

Natural selection disrupts Hardy-Weinberg Equilibrium by favoring certain alleles over others.

What is gene flow?

The transfer of alleles or genes from one population to another, which can alter allele frequencies.

What are mutations in the context of Hardy-Weinberg?

Changes in the DNA sequence that can introduce new alleles into a population.

What is sexual selection?

A form of natural selection where individuals with certain traits are more likely to obtain mates.

What does the equation p² + 2pq + q² = 1 represent?

It represents the Hardy-Weinberg equilibrium for allele frequencies in a population.

What do p and q represent in the Hardy-Weinberg equation?

p represents the frequency of the dominant allele, and q represents the frequency of the recessive allele.

How do you calculate the frequency of the recessive phenotype in a population?

The frequency of the recessive phenotype is given by q².

If 9 out of 100 kernels are yellow, what is the frequency of the yellow allele?

q² = 9/100 = 0.09, so q = sqrt(0.09) = 0.3.

In a population with 91 purple and 9 yellow kernels, what is the frequency of the purple allele?

p = 1 - q = 1 - 0.3 = 0.7.

What is the frequency of the AA genotype in a population where p = 0.6?

p² = (0.6)² = 0.36.

What is the frequency of the Aa genotype if p = 0.6 and q = 0.4?

2pq = 2(0.6)(0.4) = 0.48.

What is the frequency of the aa genotype if q = 0.4?

q² = (0.4)² = 0.16.

If the frequency of the recessive allele (a) is 0.4, what is the frequency of the dominant phenotype?

The frequency of the dominant phenotype is p² + 2pq = 0.36 + 0.48 = 0.84 or 84%.

In a sample of 215 individuals, if 150 can taste PTC, what is the frequency of non-tasters?

The frequency of non-tasters is 65/215 = 0.30.

What is the frequency of the t allele if q² = 0.30?

q = sqrt(0.30) = approximately 0.55.

How do you find the frequency of the T allele if q = 0.55?

p = 1 - q = 1 - 0.55 = 0.45.

What is the significance of Hardy-Weinberg equilibrium?

It describes a population that is not evolving, where allele frequencies remain constant.

What does it mean if a population is not in Hardy-Weinberg equilibrium?

It indicates that evolutionary forces are acting on the population, changing allele frequencies.

How can you determine the frequency of a dominant phenotype from genotype frequencies?

By adding the frequencies of homozygous dominant (AA) and heterozygous (Aa) genotypes.

If 150 out of 215 individuals can taste PTC, what is the frequency of tasters?

The frequency of tasters is 150/215 = approximately 0.70.

What is the relationship between allele frequency and genotype frequency in a population?

Allele frequencies can be used to calculate expected genotype frequencies under Hardy-Weinberg equilibrium.

In a population with a recessive phenotype frequency of 0.09, what is the expected frequency of the dominant phenotype?

The dominant phenotype frequency is 1 - q² = 1 - 0.09 = 0.91.

What is the formula to calculate the frequency of the dominant allele if the recessive allele frequency is known?

p = 1 - q, where q is the recessive allele frequency.

What does a frequency of 0.4 for the recessive allele indicate about the dominant allele frequency?

The frequency of the dominant allele would be 0.6.

In the context of genetics, what does 'p + q = 1' signify?

'p + q = 1' signifies that the total frequency of all alleles at a locus equals 1.

What defines a species?

A group of organisms capable of mating, exchanging genetic material, and producing viable, fertile offspring.

What is speciation?

The formation of new and distinct species as a result of reproductive isolation.

What are the two broad types of speciation?

Sympatric Speciation and Allopatric Speciation.

What is Allopatric Speciation?

Speciation that occurs when members of a population are geographically isolated and then become reproductively isolated.

What is Sympatric Speciation?

Speciation that occurs when members of a population stay in the same geographic area but become reproductively isolated.

Why is speciation important?

It results in diversity of life forms, allowing for more genetic variation and better survival against environmental changes.

What are reproductive barriers?

Factors that prevent different species from interbreeding and producing viable offspring.

What are the two types of reproductive barriers?

Prezygotic barriers and Postzygotic barriers.

What is a prezygotic barrier?

Reproductive barriers that occur before fertilization, preventing the formation of offspring.

What is a postzygotic barrier?

Reproductive barriers that occur after fertilization, leading to inviability or infertility of offspring.

What is habitat isolation?

A prezygotic barrier where physical separation prevents members of two species from mating.

What is temporal isolation?

A prezygotic barrier where species reproduce at different times, preventing interbreeding.

What is behavioral isolation?

A prezygotic barrier where differences in mating rituals prevent different species from mating.

What is mechanical isolation?

A prezygotic barrier where differences in reproductive anatomy prevent mating.

What is gametic isolation?

A prezygotic barrier where differences in gametes prevent fertilization.

What is reduced hybrid viability?

A postzygotic barrier where negative interactions between genes cause offspring to be frail and unable to mate.

What is reduced hybrid fertility?

A postzygotic barrier where hybrid offspring are viable but infertile.

What is hybrid breakdown?

A postzygotic barrier where the first generation of hybrids is viable and fertile, but subsequent generations are not.